Strut construction



June 7, 1932. G. M. BELLANCA Filed Nov 8, 1950 atten/m1,@

Patented `lune 7, 1932 GIUSEPPE M. BELLANCA, OF NEW CASTLE, DELAWAREsTRU'r CONSTRUCTION Application filed November rlhe invention relates toairplanes and more particularly has reference to strut members and anarrangement for the same.

In the past struts or compression memb' bers employed for bracing,between thewing surfaces of an airplane or between a wing surface andthe fuselage have generally been given a circular cross section. In somenstances a strut of this type has had a fairing l addedV thereto so asto produce a stream lined section. Other constructions have also beenemployed for effecting such a section. How-y ever, but littlevattentionhas been given to forming a strut of sufficient size and such shape asto provide a lifting surface, the art considering chiefly the advantageof eliminating parasitic resistance by stream lining the struts andmakingthem of as small a cross section as is structurally feasible.

The major object of this invention is the provision of an airplane strutprovided with a lifting surface. p

An equally important object of the invention is the designing of aconstruction alf lowing a plurality of struts Vprovided with liftingsurfaces to be attached to a wing of an airplane for the purpose ofsupporting the same.

Yet another object of the invention is the designing of an airplanestrut having a lifting surface portion adapted to be connected to thefuselage of a planeand an extension column member connected to a wing ofthe plane, the lifting surface of the strut being so positioned withrespect to the wing of the plane wit-h which it is associated as tosubstantially prevent interference between air,

currents adjacent said wing and the lifting surface.

A further object of the invention is the provision of a plurality ofstruts provided with lifting surfaces, the struts being connected to thefuselage and a wing of the plane and positioned in tandem relation onebehind the other. Y

Still a further object of the inventionv is the provision of adesignallowing the use of a plurality of lift struts, the struts beingpositioned in tandem from the leading to the trailing edge of the wingon each side of the s, 1930. serial 110.4945361.

fuselage, each strut being-connected to the fuselage and the wing, thestruts adjacent the Wing being additionally supported by a cross framewhich also ties the struts together.

Still another object of the invention is the provision of atruss'framework whereby they wing supporting end of a strut may bespaced from the wing surface and interferience of air currentsprevented. l

Still another object of the invention is th provision of a pluralityofstruts provided with lifting surfaces, the struts being connected to thefuselage and a wing of the plane and positioned in tandem relation onebehind the other, the foremost of said struts being arranged with apositive angle ofincidence and the rearmost 'with a negative angle ofincidence.

Yet a further object of the invention is` the provision of a pluralityof struts' provided with lifting surfaces, said struts being arranged soas to increase both lateral and longitudinal stability of the airplane.

lVith these and other objects in View, which may be incident to myimprovements, the invention consists in the vparts and combinations tobe hereinafter set forth and claimed, with the understanding that theseveral necessary elements comprising my invention may be variedin'construction, proportions and arrangement without departing from thespirit and scope of the appended claims.

The'invention comprehends the provision of a novel strut or Yacompression member i for supporting the wings of an airplane, and alsoincludes thepositi-oning of a plurality of struts in tandem, onebehindthe other. One method of practically effecting the concept of theinvention is the provision of a. strut having an elongated liftingsurface portion adapted to be connected tothe fuselage of the plane. rTothe lifting surface portion is secured an extension column member whichis also connected to the wing with which the strut is associated.

In use the struts on the same side of the fuselage are positionedparallel to each other and have their upper ends connected to the Wingsurface along the same chord of the wing and their lower ends connectedto the fuselage. For the purpose of strongly supporting the struts andtying them together, a novel cross frame construction which is connectedto the extension column members and the -wing is employed.

In orderto makemy invention more clearly understood, I have shown in theaccompanying drawing, means for carrying the same into practical effectwithout limiting the improvements in their useful applications to theparticular constructions which, for the purpose of explanation, havebeen made the subject of illustration.

In the drawing:

VFigure 1 is a perspective .view of an airplane havingthe struts formingthesubject matter of the-invention employed thereon.

Figure 2 is a partial sectional elevation taken along -the Aline 22 ofFigure 1 and shows in detail the connection of the struts tor' the wing.

Throughout the drawing-similar reference numerals refer to like partsinthe different views. Shown inFigure 1 is an airplane havinga-fuselagel, of the cabin type, upon which are provided V,the customarytail-surfaces 2, and rudder 3. The plane is driven by a suitable motor4tol which is connected a propeller 5. Securedto .the lower part of thefuselage is a landinggear 6, of any convenientdesign,;.provided-with-wheels 7. A tail supporting wheel 8 is alsodisclosed. Mounted uponthefuselage isa wing 9-provided with ailerons 10.

Ting 9 may be o'f-any desired airfoil section and isfformed Aofthe-usual sparsll, ribs 12, and surfacing material .13.The-.Wingconstruction maybe one of the all-metal type oritheribslandsparsmay be formed of Wood and a suitable fabric covering materialemployed.

.Forzthe purpose of supporting 'the wing 9, Izhavedisclosed a novel formof strut which comprises al lifting surface :portion 14havdrawinghas'been omitted. Upon the -spar and rib construction justmentioned, there is placed suitable surfacing or covering material 14.-.Y

There is securedto the end of the lifting surface Iportion of eachstrut, as'previously pointed out, an extension column member 16. Theextension columnmemberl is so positioned upon the lifting `surfaceportion that the center of gravity of itsI cross section coincideswith-the center of gravity of the cross section ofi the lifting-sectionportion, thus preventing the load transmitted 'tothe lifting the liftingsurface portion possesses a smaller cross section than the main body ofthe lifting surface. Because of the taperjust mentioned, the crosssectional area of the lifting surface portion progressively increasesfrom a minimum at; its end ltea maximum where the taper joins themainbody of the lifting surface.

In positioning the struts so that they may function as compressionmembers for supportingthe Wing, the endrof each extension member issecured tothe wing of Vthe-plane, V

while the free end ofthe lifting surface portion is connected to thefuselage. Therstruts are arranged in pairs on opposite sidesofthefuselage, although more ythan two on each side of the wing maybeemployed if desired. Thus there is'provided a forward strut andarcarward -strut for each semi-span ofthe wing, which haveftheir upperlor extension column ends connected tothe wing along the same wing chord.The free end ofeach eX- tension column member 12 is secured to asuitable litting 18 whichis attached to'one -of the spars of the wing. Ashort stub wing19, of any suitable airfoil design, is mounted upon eachside of the fuselage .adjacent the landing carriage, and toithis thefree end of the lifting surface of the forward strut is secured. Asshown in the drawing, thefree end of the lifting surface of the rearwardstrutzis attached directly'to the lower portionzof the fuselage withouttheuse of a stub wing.

Itis to be understood, however, that the free endsof the lifting surfaceportions of both struts may be directly connected to the fuselage orconnected thereto through the medium of a stub wing. In some instancesit may be desirable to connect the free endof the lifting surface ofthe'forwardstrut. to the landing gear of the plane. Such practice', itis to be understood, may be followed without departing from the spiritof the invention or the scope of the appended claims.

It is notedthat the forwardy lift strut of this application is shownYwith apositive angle of incidenceA and that'the rearward strut is shownwith a negative angle of incidence. This is very clearly illustrated'inFigure 2 of the-drawing. This arrangement of `struts serves to verymaterially increasethe rlongitudinal stabilityrof the. airplane.The'probable explanation of this isas followszfThe i as desired.

resultant lift on the lifting surface portion a point above the wing.Thus it willbe seen that each of these strutsvexerts a: force tending toprevent any loss of longitudinal stabil-v ity. This is of greatimportance and is a result which has been constantly sought after inairplane research and design. The attachment of the struts to the-wingis well shown in both Figures l and 2 andfcomprises a horizontal tie rod20, the endsrof which are secured,'inaiiy convenient manneryto eachofthe extension column members of the struts. The tie rod 2O issubstantially parallel to the wing and is positioned adjacent thetapered end l5 of the lifting surface of each. strut. Also connected toeach extension column member adjacent the cross tie 20, is a verticalhanger or column 21..' The upper end of each column 2l is suitablysecured to the wing. This connection may be made through means ofafitting if desired. l

For providing further bracing to the con` struction just described,crossed tie wires 22 are employed. These wires are connected adjacenttlie wing surface to the vertical 'hang er 2l an d have their other endssecured tothe lower end of the opposite hanger. In effect they providediagonal tension members of a truss construction and are placed undeitension before having their ends secured as described. Y

All of the members of the tie frame construction just described, may besuitably stream lined so as to reduce parasitic resistance.

Each extension column member may be formed integralwitli its liftingsurface portion if desired. Also it may be constructed of the samematerial as the spars and ribs of the lifting surface portion.`However,` in some instances, metal tubular construction is preferred,although it is to be understood that Lbeams, T-beams, `built-up boxgirders, or other structural beams and forms may be employed if desired.In the latter instances,

the extension column -members may becov-j ered with suitablerfabric andstream lined or any other method of stream lining may be employed.

The spars and ribs of the lifting surfaces of the struts are constructedof wood or metal Fabric` surfacing material or metal may be used forcovering the framework formed by the spars and ribs.

The advantages to be derived from a strut of this construction will atonce be apparent. Besides affording compression members for the supportof the wing, an additional lifting surface is provided. This increase inlifting surface is accompanied without the loss of efficiency of theairplane, which occurs in a triplane or biplane having the same wingsurface area as a monoplane, due to the-interference of air currentspassing adjacent yto upper and lowerwings.

By the use of the extension column members which allow the airfoilvsection of the strut to be stopped a considerable distance below thebottom surface of the wing, interference of air currents adjacent thelifting surface of the struts and the wing is substantally prevented.This interference is furtherprevented by providing the tapered portion17 near the end of the lifting surface of each strut. 1 y

Another feature of the lift strut construe tion resides `in the factthat their use increases the lateral stability of the airplane. Theresultant lift on the lifting surface portion of each strut is normal tothe strut. vIt will be appreciated that when the lines of resultant liftfor similar sections on struts directly opposite each other on differentsides of the fuselage arev drawn, they will intersect each other abovethe fuselage. This point, Vit will be appreciated is above the center ofgravity of the airplane. Hence there is always a positive force tendingto prevent the ship from losing lateral stability or to prevent it fromrolling.

The resultant lift on the struts also tends to prevent the ship frompitching downwardly and aids in controlling its longitudinal stability.Besides thez effect of aiding the longitudinal stability the struts areofbene.- fit in: that theyl may be so positioned as to allow the planeto climb at an increased angle of attack.

While the invention has been shown as applied to a monoplane of thecabin type, it will beunderstood that the invention may be associatedwith other types of monoplanes asv well as biplanes `and triplanesj Whena multiwing ship has the strut construction forming the subject matterof this invention employed therewith, the struts may be either connectedto the fuselage or to the upper wing surface of a lower plane.

From the foregoing description it will be appreciated that I haveprovided a novel strut construction for'an airplane which not onlyprovides compression members for supporting the wing, but also affords alifting surface portionwhereby the eective Wing area'of the planeisincreased. It is also to be observed that a strong and rigid bracino'for the struts'of the invention when arranged intandem relation has beendevised. With the use of struts in tandem not only is the stability ofthe plane greatly increased but a more rigid and stronger support forthe wing surfacing is provided. Y

While I have shown Aand described the preferred embodiment of myinvention, I wish it to be understood'that I do not confine myself tothe precise details' of construc- ,y tion herein set forth, by way ofillustration,

as itis apparent' .that manych-angesV andavari-V ations may be r madetherein, .byfthosef skilled in the art, .Without departing from.thelspirit ofthe inventionor exceeding the sc'opeof the appendedclaims. i f

Iclaim Al. .In an airplane,I a plurality-offWingfsupportlng struts atileast onezof saidrstrutshav-1 ing an. airfoilsurface permanentlyarranged with a negativeangle-of'incidence 2. In anv airplane, a@plurality of .Winggsupporting struts, at least two ofsa'idistrutszh'aving airfoll surfaces permanently AVarranged withdifferent. angles :of incidence.

3. In an airplane, a pluralityjofWing-supportingstruts, at least one ofsaid strutshaving anvairfoill surface permanently arranged with :apositive angle of incidence, and at least vone Vother of. said..strutshaving an airfoil surface permanently .arranged with ;a differentangle of incidence from said'first mentionedstrut. l

. 4. lngan airplane, a plurality o'fwingi-supporting struts, :theforemost of sai d strutsv having an a-irfoilsurface permanently arrangedWith av positive angle of incidence, and the'rearmost of said strutshaving an airfoil surfacepermanently arranged With a different Vangle ofincidencefrom said 4foremost strut.

-5. In an airplane, a plurality of Wingsupporting struts, at least `oneofsaid struts having an airfoilsurface permanently arranged Vwith apositive angle Vof incidence, and at least one otherofzsaid.strutshaving an airfoil surface permanently arrangedlwith a.negative anglev of incidence.

16. In ranv airplane, a plurality .ofivving-:supporting struts, the`foremost :of said struts having -anairfoil surface ypermanentlyarranged with'a positive angle of'zincidence, and the rearmost of'saidstruts havinjgran ai-rfoil surface .permanently farranged 'With anegative angle of incidence 7. .In an. airplane,- a'wvingi-supporting`strut having an airfoil surface With:a:permanent negative .angle ofincidence.

8. :An airplane comprising, in combination,A a fuselage, a sustainingWing extending laterally 'from each -side ofthe 'top rof said fuselage,a stub .Wing projecting laterally from each side of said fuselage at:the bottom of samepving *supporting -strut members J attached totheouterI ends of each` of said stub Wingsy and tothelower-'surfacesoffeach 'of said Vsustaining Wings, `other'tvingsupporting-strut members attached tothe s ides'of the` fuselage atlits bottom "and'tto fthe lower surfaces of ,each ofsaidxsustainingVWings, said first mentioned strut members having Iairfoil surfaces withpositive -ang'les of incidence, and said secondmentioned strut'me'mbershaving airfil Ysurfaces `With inegative anglesoflincidence.

;9. An airplane fcompr1sing,.a. fuselage, fa

sustaining 'wing extending :laterally from each side ofthefuselageaplurality ofstruts having an airfoil i surface extending 1from each side of saidlfuselageto :saidsustaining Wing, the Yforemost ofsaid lstruts permanently arrangedwith apositive angle of incidenceandlthezrearmost of saidxstruts permanently arranged With anegativeangle of incidence. 10. A n airplane comprising affuselage,.a sustainingWing .extending laterally from eachside of the fuselagesaid sustainingWing'being provided on each side with an` aileron, a plurality of strutseach-having -anairfoil-surface extendingfrom each side of said fuselage-to said ysustaining wing, the foremost of said struts permanentlyarranged With a positive angle ofincidence andthe rearmost of saidstruts permanently arranged-With afnegative yangle of incidence.

11. An airplanercomprisingga fuselage,.a sustaining Wing extendinglaterally: from each side of the top of thefuselage, aplurality ofstruts each having an airfoil surface, one end of each of said strutsbeing connected to said fuselage andthe other endof said struts havingan extension `member of smaller cross-section for connectionto thesustaining Wing, the foremost of saidstrutsfpermanently arranged-With apositive angle of incidence and therearmost of saidstrutspermanentlyarranged with a negative incidence. 12. An airplane, comprising afuselage, a sustaining Wing `extending laterally from each side of thetop of the fuselage, a plurality'of strutseach having an airfoilsurface, one end of eachofsaidstruts being connected tothe fuselage .andthe other end-of said struts having an extension memberof smallercross-section for connection .to ythe sustaining Wing, a vbracing memberypositioned between the extension membersl on each side of the fuselageand members eX- tending verticallyffrom said bracing member to thesustaining wingzfor'providing an additional support -for each of saidstruts, the foremost of said strutspermanently'arranged With a positiveangle of incidence and the rearmost of Said struts permanently arrangedwith a negative angle ofxincidence. In testimony WhereofI affix mysignature.

GIUSEPPE 'M. BEILANCA.

